In the production of soft pet foods that are semi-moist or dry in moisture content, several methods have been used to make products with the appearance of marbled meat. In a patent issued to Bone, U.S. Pat. No. 3,330,832, a method is disclosed in which a binder of sticky caseinate salt is used to bind extruded sheets of red and white semi-moist pet food into a marbled meat-like loaf. A patent issued to Charter, U.S. Pat. No. 3,765,902, improves on the method of the Bone patent by co-extruding strands of white pet food within the red pet food, but still uses the caseinate salt to bind the two pet foods. Another patent issued to Bone, U.S. Pat. No. 4,029,823, discloses a soft, dry pet food resembling marbled meat in which two pet foods are co-extruded with a proteinaceous adhesive like collagen or a caseinate salt to bind the two pet foods. Although these processes are successful for making marbled pet food products, using caseinate binders is also expensive. It would therefore be desirable to make a less expensive marbled meat-like pet food without caseinate binders.
In U.S. Pat. Nos. 4,358,468 and 4,372,734, Dolan et al have disclosed a process by which a marbled pet food may be produced by applying pressure to bind dissimilar meat and fat phases during partial mixing of the co-extruded phases in a rectangular mixing compartment having stationary mixing elements.
It is therefore an object of the present invention to provide a low-cost semi-moist or dry pet food having the appearance of marbled meat and acceptable palatability to animals.
It is also an object of the present invention to provide a marbled pet food which does not require caseinate binders.
It is also an object of the present invention to provide a method and apparatus for continuously making a caseinate-free marbled meat pet food.
It is also an object of the present invention to provide a method and apparatus capable of making marbled meat pet foods with a variety of marbling patterns.